I would suggest running the Intel® Processor Identification Utility to determine if your processor supports Enhance Intel SpeedStep® Technology, if it does, then make sure to disable it from the BIOS, since this feature forces the processor to run slower in order to save power consumption.

If the processor does not support Enhance Intel SpeedStep® Technology, then I would suggest contacting the motherboard manufacturer to make sure the processor is listed as compatible with your particular motherboard.